Whether you use Windows or Linux, the Windows key is the foundation of many useful keyboard shortcuts. You know, hold it down plus some other key.
Whatever your preferred OS, look them up! You may find a few you would like to start using.
But yeah, on my work computer which is a Windows machine, I often use it to open the start menu and start typing the name of the app I want to launch. It’s faster than clicking on an icon somewhere if your hands are already on the keyboard.
C seems like an awfully painful way to write the CRUD apps most of us spend our time on.
And any performance gains would be invisible in most situations where network I/O is the biggest bottleneck (almost) regardless of the language used.